gistfile1.rb

$sessions = {}
class Test
  def initialize(session, &blk)
    $last_session = session
    yield
  end
end

class User
  def initialize
    $sessions[to_s] = $last_session
  end
  def self.find(id)
    User.new
  end

  def say_hey
    puts "hey from session #{$sessions[to_s]}"
  end
end

Test.new('test1') do
  User.find(1).say_hey
end